There is a very good article, Ebooks and Interlibrary Loan: Licensed to Fill? in the Journal of Interlibrary Loan, Document Delivery, & Electronic Reserve. The publisher, Taylor and Francis, is offering free access to the article. The article discusses the issues surrounding interlibrary loan and electronic books. The full citation and abstract, from Taylor and Francis, are below.
Linda Frederiksen, Joel Cummings, Lara Cummings & Diane Carroll (2011): Ebooks and Interlibrary Loan: Licensed to Fill?, Journal of Interlibrary Loan,Document Delivery & Electronic Reserve, 21:3, 117-131. http://dx.doi.org/10.1080/1072303X.2011.585102
Abstract: Increasingly, libraries of all types and sizes are adding electronic book (ebook) titles to their collections. A survey was used to explore the implications of ebook licensing and interlibrary loan use. Among academic libraries in the United States, a widespread preference for handling print books was found along with a need for more information about ebook interlibrary loan rights at one’s own institution and a means to identify format type available from potential lending libraries.